The polls have closed in a referendum that could determine the future of the United Kingdom. At stake is whether Britain remains in the European Union. Our colleague Robert Siegel is in London this week reporting on the vote known as Brexit, as in British exit. Earlier this evening I spoke to him. He was at a counting center where people were hand-counting the ballots.

Describe the scene. What's going on there?

ROBERT SIEGEL, BYLINE: Well, I could say it's all over but the counting, but the counting is quite an operation tonight. I'm at the Civic Suite in the town hall complex of Wandsworth in southwest London. And in this area which is a - very much a remain stronghold, it's expected to go very heavily in favor of staying in the EU. A couple of hundred people are counting ballots as boxes full of them arrive from the various polling stations.

The first task is just to see how many people voted, and then will come the task of seeing how many voted to stay and how many voted to remain. For each of those couple hundred people doing that, there's typically somebody looking over his or her shoulder doing an informal count and reporting back to one of the campaigns to try and figure out what's going on and create a model of the returns.

SHAPIRO: Sounds like a very painstaking process. Are we going to know the results before sunrise?

SIEGEL: (Laughter) Sunrise in Britain, it could be close. But I think people in the U.K. are going to go to sleep not knowing the result in all likelihood.

SHAPIRO: Talk about what's at stake here. Obviously a vote to remain is more or less the status quo. But a vote to leave - what kinds of consequences would that trigger?

SIEGEL: The least consequences would be political careers being cut short. David Cameron would probably not survive very long as prime minister. The conservative party which has been divided for decades over its policy on Europe - if they won the leave vote, that question would be decided in favor of the so-called Euro-skeptics or the anti-Europeans.

Then comes the absolute unknown of what happens to Britain's trading relationships with Europe and with other countries where trade is now governed by EU deals. We just don't know whether U.S. companies will continue to invest here if it isn't the springboard into Europe. That's in the event of a Brexit vote. Of course, we don't know that that's - what the result is going to be.

SHAPIRO: You've been speaking with voters all week in the U.K. Can you generalize what tends to motivate the people who want to leave the EU and what tends to motivate those who want to stay?

SIEGEL: Those who want to leave express a real anxiety about losing control of the country as they understand it. That's expressed by immigration. If you're a member of the EU, any citizen of any EU member country may live and work in your country. And that's resulted in a very big increase in immigration from East European countries here. So that's one.

But generally the sense that Brussels is an undemocratic place, it's not the old U.K. that people knew and they've lost control over the people who come up with the laws that govern them. It may be an exaggeration, but it's one that I've heard quite a bit.

SHAPIRO: And the people who wish to remain?

SIEGEL: People who wish to remain - well, first of all, they are a lot of young who have only known growing up in the European Union. Young voters are very strongly in favor of remain. They have traveled and worked all over the continent. Those in university have very often been able to study in other countries. Many will actually describe themselves as having a European identity in addition to a British one. So there are those.

And there are those that may not like the EU very much, but they say you have to be part of a big group to compete in the world economy. And Britain on its own, they would say, can never do that as well as Britain within the EU.

SHAPIRO: That's our ALL THINGS CONSIDERED co-host Robert Siegel speaking with us from London. Thanks, Robert.